Department of Homeland Security Secretary Kirstjen Nielsen schooled a Democratic senator on the law during a Tuesday congressional hearing on illegal immigration.

Sen. Patty Murray asked Nielsen if DHS is weighing the use ways other than detention to handle illegal immigrants, and Nielsen explained that if they are dealing with criminal illegal immigrants then they turn that person over to U.S. Marshals and there is no alternative to detention.

“I just want to say again — if you cross in between the ports of entry…” Nielsen started.

Murray then suggested that Nielsen’s opposition to illegal immigration is part of her political philosophy rather than her duty to follow the nation’s laws.

“I know what your philosophy is,” Murray said, cutting her off.

“It’s not a philosophy, it’s a law Congress passed,” Nielsen said exasperatedly. “So those people need to come to the ports if they want to seek asylum.”